Amid an outpouring of condolences after last week’s deadly shooting at a Connecticut elementary school, the reaction from one gun-rights group stood out.

“Blood is on the hands of members of Congress and the Connecticut legislators who voted to ban guns from all schools in Connecticut,” Gun Owners of America said in a statement Dec. 15, a day after a gunman killed 27 people, including 20 first-graders, in Newtown, Conn. “They are the ones who made it illegal to defend oneself with a gun in a school.”

The explosive comment from an advocacy group with more than 300,000 members that is capable of raising tens of millions of dollars and has the ear of many conservative members of Congress underscores the difficulty that Democrats face passing any legislation that seeks to curtail access to guns.

Already, some gun control advocates are beginning to lay out specific policy proposals in response to the Connecticut shooting. Sen. Dianne Feinstein, D-Calif., said she will reintroduce a version of the expired 1994 assault weapons ban and a proposal to ban magazine clips “of more than 10 bullets.” Sen. Joseph I. Lieberman, the retiring Connecticut Independent who caucuses with Democrats, advocated for the creation of a national commission on violence.

Such proposals, however, are likely to run into the opposition not only of the National Rifle Association — one of the most formidable lobbies in Washington — but also from Gun Owners of America, a smaller, Springfield, Va.-based group that argues even more emphatically that the answer to mass shootings is to give Americans more, not less, access to firearms.

The two advocacy groups are often at odds on both strategy and messaging, even engaging in occasional backbiting, but together they have successfully blocked all major gun control measures since 1994. In the wake of the Dec. 14 massacre, the NRA denied reporters’ interview requests and shuttered its Facebook account, while the GOA seized the spotlight.

“They go into possum mode every time something like this happens,” said Mike Hammond, the group’s legal counsel who worked for 12 years as legal counsel to the Senate Steering Committee. “That’s the reason why we exist.”

Gun-control advocates say the GOA makes inflammatory statements to distract the public from middle-of-the-road policy solutions and to raise money from supporters.

“I think they get a lot more attention than they deserve, as people who make outrageous comments often do,” Jonathan Lowy, director of the Legal Action Project at the Brady Center to Prevent Gun Violence, said.

The group operates on a slim budget of just less than $2 million compared with the NRA’s $71 million in 2010, according to the most recent tax filings available. Still, it is widely seen as a major player in the debate over firearms on Capitol Hill. Rep. Ron Paul, R-Texas, has praised the group as “the only no-compromise gun lobby in Washington” — and it frequently outspends the NRA on lobbying activities.

He said the group is already working with Rep.-elect Steve Stockman, R-Texas, to introduce legislation early next year that would repeal gun-free school zones. Stockman was one of a handful of Republican lawmakers who benefited from the group’s largesse this election cycle. The GOA put more than $23,000 behind Stockman, a no-holds-barred conservative member of the 1994 freshman class who is returning after a 15-year hiatus.

The NRA spent almost $18 million through its political action committee and the affiliated Institute for Legislative Action trying to influence congressional elections this cycle. The GOA invested only $89,000 in a handful of races, according to the Center for Responsive Politics, preferring instead to exert pressure under the Capitol Dome. The group spent almost $900,000 from Jan. 1 to Sept. 30 fighting dozens of gun control measures, federal records show.

The GOA often finds itself clashing with its more moderate counterpart. After the Columbine High School shooting in 1999, the NRA backed a compromise package of gun control measures. The GOA spent more than $3 million every year from 1999 to 2002 to successfully oppose it.

Since then, the GOA’s lobbying expenditures have dropped considerably, as legislative efforts to curb gun use fizzled. But Hammond pledged an uptick to fight a slew of proposals expected in the beginning of the 113th Congress.

At least one House Republican took to the airwaves Sunday to echo the group’s response to the Connecticut shooting. Rep. Louie Gohmert, R-Texas, argued that the elementary school principal who tried to stop the massacre would have been more successful if she had been armed.

“I wish to God she had had an M-4 in her office, locked up so when she heard gunfire, she pulls it out and she didn’t have to lunge heroically with nothing in her hands, but she takes him out, takes his head off before he can kill those precious kids,” Gohmert said.

The gun-rights group argues that gun-free zones leave citizens vulnerable to attacks without the ability to defend themselves in kind.

After a gunman killed 12 people and wounded 58 more at a crowded movie theater in Aurora, Colo., in July, the group said congressional Democrats were partly to blame for the massacre. It also praised George Zimmerman, the Florida neighborhood watch volunteer who ignited a national controversy months earlier when he fatally shot an unarmed teenager he considered suspicious.

Democrats “appear oblivious to the fact that their anti-gun mentality created a deadly situation in Aurora, Colorado, where there was a room with a number of trained military marksmen — and none of them were allowed to have a gun,” the GOA wrote in a fundraising email to supporters. “Any of those individuals could have made a big difference. Heck, does anyone doubt there would have been a different outcome if George Zimmerman had been in the room?”